Passive Summoner Spells
You know how a minority of summoner spells like Clarity, which used to have a greater impact during the early days of League, no longer seem ideal for ranked and LCS? What if instead of using active summoner spells which would be ineffective late game, what if a passive version of a summoner spell could be implemented, which would have a continual impact throughout the game that benefits the player or hinders the opponent?
Pro: Would either scale late game, giving the player more breathing room for OR Give an advantage/protection for a certain champion early game that is turned off after so many levels, cs, or kills/assists/deaths
Con: Slot is used up. Summoner spells are identified to be passive or active. Reduces complexity for sheer power.
Notes: Timers decrease while not taking damage from enemy champions, but also when killing enemy minions. This bonus can be increased for jungler monsters. Also, timers are something I'm not completely sure how to balance for you, but if you have a suggestion I'd like to hear it. Implementing passive summoner spells allows a more forgiving playstyle of League of Legends, which is ideal for players who are just starting out, but maybe annoying for experienced champions. Active versions, when it comes to numbers, will always be stronger than the passive version. This might not work for all champion spells like exhaust and ignite, which become either situational, delimiting, or snowbally. The purpose of passive summoner spells is to enable, not disable, champions and certain playstyles. A passive and active version of the same summoner spell cannot take both slots of the summoner spells. Implementing passive summoner spells could require a buff for active summoner spells or cause a meta shift.
Cleanse - P: A halo of quicksilver sash orbits the player, preventing one debuff effect.
Pro: Prevents snags and 100-0. Does not pop against constant cc like 
Ultimate or 
Silence. Ideal on mid and adc.
Con: Very easy to pop. Hinders certain champions that rely on CC to combo. Would be incredibly annoying if team comps are not properly made. Items like 
would pop these all the time or 
ultimate would become rubbish without buffing.
Timer: 90-240 Seconds. (1 1/2 minute to 4 minutes)
Clarity - P: Aura: All friendly champions within a radius of 
gain 0.1-1% of maximum mana back whenever an enemy minion is killed. If an ally champion within the radius dies, the summoner spell is put on cooldown. This applies to the champion with the summoner spell as well.
Pro; Ideal for seiging. Allows mages who run on empty to do a just a bit more. Turned off by successful engages.
Con: Does not do much for an individual. Might cause supersynergy for some champions.
Timer: 300 seconds. (5 minutes)
Clairvoyance - P: Whenever a champion walks past a ward placed by the champion who put it down and has the summoner spell, they are shown globally for 1 or (0.33 x champion level) seconds, whichever greater. Pro: Works against stealth champions and through brushes, enemy champions will know if they are being spotted by the ward if the champion has the summoner spell. Pink wards do not trigger summoner spell. Works well for support. Con: Makes wards very easy to clean up. Only ideal to prevent sudden ganks, but not constant vision. Does not provide extended vision UNLESS the champion places a ward with the summoner spell up to pursue. The spotted champion can simply stay still to bluff. Timer: 30-120 seconds (120 - 5 x (champion level)) (1/2 minute to 2 minutes)
Ghost - P: Gain 1% movement speed while pursuing or fleeing a champion every second, up to ((champion level) /2)% or 5%, whichever greater. Net direction is crucial because moving back and forth will not net movement speed. Not moving will decrease stacks of movement speed. X stacks are lost if damage is taken. Champion kill will always put summoner spell on cooldown. Pro: Makes some pretty sick engages/kites. Enemy champions can bait to move in the opposite direction to reduce stacks. Con: Might become mobility creep, though it does not apply instantaneously. Stacks are lost from damage over time. Timer: 300 seconds (5 minutes)
Teleport - P: If a structure is taking damage, the champion can choose to go to that structure to protect it. An orb is placed down by the summoner before teleporting. This functions equal to a normal teleport, and can be canceled as well. After X seconds, the champion returns to the orb. Pro: Supports protective play of objectives. Works well before teamfights. Orb cannot be moved or destroyed, and hidden in brushes. Con; Does not work while teamfights are occuring. Can become bait. Timer: 240-300 seconds. (3 to 5 minutes)
Barrier - P: Whenever this champion lose more than X% or current health under 5 seconds, received damage is halved for 0.5 + (champion level /2) seconds. The effect length and strength is doubled while under crowd control.
Pro: Gives champion time to react unless the enemy team uses 
to secure kill.
Con: Hard to ensure kill with barrier up. Might become useless if passive is popped or not activated.
Timer: 120 seconds. (2 minutes)
After so many champion levels, some passive summoner spells can be disabled to prevent unkillable carries or turtling. This idea has probably been suggested before, but its an idea that has been rolling around in my mind for a while. Think of the timers being related that League games can be divided into 30 minutes, and anything after 30 minutes becomes an extended late game.